Westinghouse 903915A Air Handler Control Board

Product Description

The WESTINGHOUSE 903915A is a replacement control board designed for variable speed indoor air handler units. It serves as the main electronic control interface, managing blower motor operation, thermostat signal processing, and system sequencing within the air handler cabinet. This board is a direct OEM-style replacement intended for installation by licensed HVAC technicians servicing residential variable speed air handler systems. It governs the communication between the low-voltage thermostat inputs and the ECM blower motor drive, making correct identification of the compatible unit essential before ordering.

This control board is used in variable speed indoor air handler applications, specifically in B4VM and B4VM-B series units. Compatible part numbers include B4VM-036K-C, B4VM-048K-C, B4VM-060K-C, and B4VM-B-X48K-CB. These are typically residential split-system air handlers installed in conditioned or semi-conditioned spaces, paired with a remote condensing unit. The board is mounted inside the air handler cabinet and interfaces with the ECM motor, thermostat wiring, and safety controls.

Key Features

• Direct replacement control board for B4VM and B4VM-B series variable speed air handlers
• Compatible with multiple tonnage configurations including 036K, 048K, and 060K units
• Designed to interface with ECM blower motor and low-voltage thermostat controls
• OEM-style fit reduces retrofit time and eliminates field modification

Compatibility

Designed for use with WESTINGHOUSE variable speed air handler models B4VM-036K-C, B4VM-048K-C, B4VM-060K-C, and B4VM-B-X48K-CB in the B4VM and B4VM-B series.

Installation Notes

Installation should be performed by a licensed HVAC technician. Disconnect all power to the air handler at the disconnect switch and verify zero voltage with a meter before removing the existing board. Handle the control board carefully to avoid electrostatic discharge damage to onboard components. Reconnect all low-voltage and line-voltage wiring according to the existing harness layout and verify operation through a full system cycle after installation.

Technical Specifications

• Item Type: Control Board
• Application: Variable Speed Air Handler
• Compatible Model Series: B4VM, B4VM-B
• Compatible Part Numbers: B4VM-036K-C, B4VM-048K-C, B4VM-060K-C, B4VM-B-X48K-CB

Standard Information

• Brand: WESTINGHOUSE
• Manufacturer Part Number: 903915A